This invention relates to caps for mounting on the top of aerosol cans or the like, and particularly to a tamper-resistant cap that is disengageable from an annular lip formed on the can using a cap-removal tool such as a flat blade screwdriver. More particularly, this invention relates to a tamper-resistant cap having a rigidified lift pad that is located to lie in spaced-apart relation to the annular lip on the can when the cap is mounted on the can and engage the cap-removal tool during removal of the cap from the can.
Everyone has seen an aerosol can provided with a plastic cap mounted on top of the can to cover the aerosol spray button. To release the pressurized contents of the can, it is customary to remove the cap, hold the can upright, aim the discharge opening in the right direction, and depress the aerosol spray button. Such caps are typically formed in a mold using a plastics material such as polypropylene or high-density polyethylene. The caps are usually molded to include a shell and various internal ribs and flanges. Of course, these molded caps can also be used to cover the discharge openings provided in containers other than aerosol cans.
A "necked-in" can is one type of aerosol can that is usually made of steel and includes a cylindrical body, a dome-shaped closure member coupled to the top of the cylindrical body to form an annular lip around the top edge of the cylindrical body, and a spray button mounted in the dome-shaped closure member and configured to control discharge of pressurized material in the can. One example of a conventional necked-in can is shown in U.S. Pat. No. 5,337,912 to Jochem.
It is known to make plastic caps for mounting on cans to cover the spray button mounted in the dome-shaped closure member. See, for example, U.S. Pat. No. 5,337,912 to Jochem (necked-in can) and U.S. Pat. No. 3,460,708 to Vollers (straight-wall can). It is also known to form a plastic cap for a straight-wall can to include a lower edge for engaging a tool such as a flat blade screwdriver that can be used to remove the cap from its initial tamperproof position on the straight-wall can. See, for example, U.S. Pat. No. 3,414,167 to Osrow and U.S. Pat. No. 3,334,769 to Gach.
What is needed is a tamper-resistant cap for a necked-in can that has a tool-engaging lift pad that is located and configured to disallow a person from using a cap-removal tool improperly in a way that might inadvertently puncture the dome-shaped closure member in the necked-in can during removal of the cap from the necked-in can. Consumers would also appreciate a cap having a reinforced lift pad that is provided with sufficient structural rigidity to withstand tool pressure created during cap removal.
According to the present invention, a cap is provided for mounting on a can. The cap includes a shell formed to include an interior region and a tool-receiving aperture opening into the interior region. A ridge is appended to the shell and positioned to lie in the interior region of the cap. The interior ridge includes a downwardly facing lift pad that is arranged to define an upper boundary of the tool-receiving aperture. The lift pad lies in spaced-apart relation to an annular lip on the can once the shell is mounted on the can so that a cap-removal tool can be inserted into the interior region of the shell through the tool-receiving aperture to engage the annular lip on the can and the lift pad on the interior ridge inside the cap.
In preferred embodiments, the cap includes a round top wall and a cylindrical side wall appended to the top wall. The side wall is formed to include the tool-receiving aperture that is located along a lower edge of the side wall so that it provides access to the annular lip on the can once the cap is mounted on top of the can. The side wall includes an interior surface and the interior ridge is appended to the interior surface at a location just above the tool-receiving aperture. The interior ridge is arranged to project inwardly from the interior surface toward a central vertical axis of the cap extending through the center of the top wall.
The interior ridge includes a mass of material in the interior region of the shell overlying the horizontally extending lift pad located just above the tool-receiving aperture. This material rigidifies the interior ridge and its lift pad to provide sufficient structural rigidity to withstand tool pressure applied to the lift pad during cap removal.
The interior ridge and its lift pad are positioned above the tool-receiving aperture to disallow a person from using a cap-removal tool such as a flat blade screwdriver improperly (e.g., inserting the blade tip at a steep angle upwardly into the interior region of the cap) during cap removal in a way that might inadvertently puncture a dome-shaped closure member provided at the top of the cap and located to be covered by the cap. Essentially, the downwardly facing lift pad on the interior ridge will engage the blade tip of a flat blade screwdriver that is inserted upwardly into the tool-receiving aperture at an angle to the central vertical axis of the cap other than 90.degree.. Provision of the lift pad on the interior ridge thus blocks inward movement of the blade tip toward engagement with the dome-shaped closure member of the can without blocking the type of engagement between the blade tip on the lift pad of the interior ridge and the annular lip of the can needed to allow a person to use the screwdriver to pry the cap off the can.
In a preferred embodiment, the cap further includes a cylindrical interior sleeve depending from an interior surface of the top wall and lying in the interior region of the shell. The interior sleeve includes a flange that grips a top portion of the dome-shaped closure member to hold the cap in a mounted position on the can and position the tool-receiving aperture formed in the side wall adjacent to the annular lip on the can.
In use, the cap is mounted on a "necked-in" can having a body and a dome-shaped closure member coupled to the body at an annular lip. The cap is configured so that the lift pad lies above and in spaced-apart relation to the annular lip on the can when the cap is mounted on the can. A tool such as a flat blade screwdriver can be inserted through the tool-receiving aperture in the side wall so that the blade tip extends into the interior region of the shell and engages the annular lip and the overlying lift pad of the interior ridge. The user then rotates the handle of the screwdriver to turn the flat blade so as to "lift" the lift pad away from the annular lip on the can and "break" a releasable connection between the interior sleeve flange and the top portion of the dome-shaped closure member to facilitate removal of the cap from the can.
Additional objects, features, and advantages of the invention will become apparent to those skilled in the art upon consideration of the following detailed description of preferred embodiments exemplifying the best mode of carrying out the invention as presently perceived.